Lead-acid storage batteries have long been an efficient and effective source of power for a variety of applications. From every indication it is clear that such batteries will continue in heavy use into the indefinite future. While much work has been done to develop nickel-cadmium batteries, nickel-iron batteries, lithium, sodium-sulphur systems and other electrochemical storage systems, and other alternative power sources, lead-acid batteries remain and are likely to remain the best choice for strong reasons, including their relatively low cost.
The economy and dependability of lead-acid storage batteries make such batteries practical for a vast number of applications, including stand-by power systems for communication and emergency lighting, automotive and truck-starting applications, electric vehicles, wheel chairs, uninterruptable computer power supplies, and systems for solar and wind power storage, to name just a few.
The manufacturing of lead-acid batteries is a capital intensive process that currently requires a considerable amount of production machinery and floor space. This is because current lead-acid battery manufacturing process have changed very little in the past 30 years.
A significant disadvantage to conventional lead-acid storage battery construction is the many separate electrical connections which must be made within the battery as separate welding operations. Conventional lead-acid storage batteries have intercell connections inside the battery just under the top wall.
In a standard twelve-volt battery, such connections are typically made by first punching an intercell connector hole in five battery container partitions with a container Hole Punching Machine. Once the connector hole has been punched, an upstanding projection from a plate bridge of one cell is welded, through the hole, to an upstanding projection from the plate bridge of the adjoining cell. These welds are typically made above the top of the plates in the headspace of the battery.
In addition to the intercell weldmates, battery plates for six cells are welded together onto plate straps to create cell groups on a Cast On Strap Machine. These cell groups are then placed into the battery container where they are welded to one another--through the five partitions--with an Intercell Welding Machine.
After the cell groups are welded in place, a battery cover is heat sealed onto the battery container with a Cover Sealing Machine. Next, the two external terminals of the molded cover are welded onto the battery's internal end cell posts using a Post Bonding Machine. It is apparent that the process of making these welds and connections is time consuming, unduly expensive and includes the possibility of miswelds and broken welds.
Along with requiring a substantial capital investment, the multiple machines, machine operations and process variables used in the conventional manufacturing method present numerous production problems. For example, five separate machines are employed to make batteries in the conventional manner as described above. In order to operate correctly, each individual machine must be set for a given size of battery. Because the machines do not always operate at the same speeds, a conveyor is required to be placed between the machines to store batteries and compensate for production rate variables.
Additionally, because each machine must be operated individually, at least one operator per machine is generally needed. This can create problems with productivity in that if one machine has to be shut down, the entire production line stops.
Finally, a significant amount of floor space is required to house these five machines and the conveyors between them. Although production line lengths vary, a length of 250 feet is not unusual.
A method of manufacturing batteries that would eliminate the need for several expensive pieces of equipment including cast on machines and cell stackers would be an improvement in the art.